1. Field of Invention
The present invention generally relates to the field of medical devices. Some embodiments of the invention relate to instruments used during surgical procedures to install a spinal implant in a human spine. Some embodiments of the invention relate to instruments used in evaluating and/or preparing a disc space for a spinal implant. Some embodiments of the invention relate to an instrument used to manipulate and/or position a spinal implant between human vertebrae.
2. Description of Related Art
An intervertebral disc may degenerate. Degeneration may be caused by trauma, disease, and/or aging. An intervertebral disc that becomes degenerated may have to be partially or fully removed from a spinal column. Partial or full removal of an intervertebral disc may destabilize the spinal column. Destabilization of a spinal column may result in alteration of a natural separation distance between adjacent vertebrae. Maintaining the natural separation between vertebrae may prevent pressure from being applied to nerves that pass between vertebral bodies. Excessive pressure applied to the nerves may cause pain and/or nerve damage. During a spinal fixation procedure, a spinal implant may be inserted in a space created by the removal or partial removal of an intervertebral disc between adjacent vertebrae. The spinal implant may maintain the height of the spine and restore stability to the spine. Bone growth may fuse the implant to adjacent vertebrae.
A spinal implant may be inserted during a spinal fixation procedure using an anterior, lateral, posterior, or transverse spinal approach. A discectomy may be performed to remove or partially remove a defective or damaged intervertebral disc. The discectomy may create a space for one or more spinal implants. The amount of removed disc material may correspond to the size and type of the spinal implant or spinal implants to be inserted.
Spinal surgery may be complex due in part to the proximity of the spinal cord and/or the cauda equina. Preparation instruments and spinal implants may need to be carefully inserted to avoid damage to nerve tissue. Alignment and spacing of a spinal implant that is to be inserted into a patient may be determined before surgery. Achieving the predetermined alignment and spacing during surgery may be important to achieve optimal fusion of adjacent vertebrae.
U.S. Pat. No. 6,682,534 to Patel et al., which is incorporated by reference as if fully set forth herein, describes an endplate preparation instrument for preparing endplates of adjacent vertebral bodies. The instrument includes an elongated member that rotates in a housing member. The elongated member includes a cutting element that penetrates and removes bone from the endplates when the elongated member is rotated.
U.S. Pat. No. 6,599,294 to Fuss et al., which is incorporated by reference as if fully set forth herein, describes a surgical instrument for introducing a spinal implant between two vertebrae. The instrument includes two mutually opposing guide bodies. The guide bodies combine to form a guideway for lateral insertion of a spinal implant in the intervertebral space.
Some spinal implants may be inserted using a lateral (transverse) approach. U.S. patent application Ser. No. 10/633,371 to Mitchell at al., which is incorporated by reference as if fully set forth herein, describes spinal implants that may be inserted using a lateral (transverse) approach.